Study On Productivity And Soil Properties Of A Middle Aged Mixed Forest Plantation Of Michelia Fujianensis And Cunninghamia Lanceolata

In this article, a 13-year-old mixed forest plantation of Chinese fir (Cunninghamia lanceolata) and Michelia fujianensis (proportion was Chinese fir : M. fujianensis=3:1), a 13-year-old pure plantation of Chinese fir and a 10-year-old pure plantation of M. fujianensis in Jian'ou, Fujian, China were sampled and their stand volume, tree layer biomass, soil properties, stem taper equation and stem form of the M. fujianensis were studied. The wood physico-mechanical properties of M. fujianensis from plantation and natural forest were determined and compared. The main results were as follows:(1) The productivity of the 13-year-old mixed forest plantation of Chinese fir and M. fujianensis was closed to the pure plantation of Chinese fir. Stand volume of the 13-year-old mixed plantation forest of Chinese fir and M. fujianensis (209.83 m³Â·hm^-2) was only as much as 96.57% of the pure Chinese fir plantation, but tree layer total biomass (112.13 t·hm^-2) was as much as 104.53% of the pure Chinese fir plantation. Mean annual increment of stand volume in the mixed forest plantation (16.14 m³Â·hm^-2·a-1) was 1.37 times as much as in the pure M. fujianensis plantation, but mean annual increment of tree layer biomass was 1.02 times as much in the mixed plantation as in the pure M. fujianensis plantation. Although mean annual stand volume increment was lowest among the 3 stands, but its mean annual increment of tree layer biomass was 1.02 times as much as in the pure Chinese fir plantation.(2) Top soil properties of the 13-year-old mixed forest plantation of Chinese fir and M. fujianensis improved at certain degree. Compared to the pure plantation of Chinese fir and M. fujianensis, the mixed plantation of Chinese fir and M. fujianensis increased top soil (0-10 cm) organic matter by 3.27% and 7.85%, respectively, increased hydrolysis N by 16.42% and 23.68%, respectively, increased available P by 1.15% and 4.74%, respectively, increased available K by 10.03% and 14.29%, respectively, and increased pH value by 5.80% and 10.20%, respectively. (3) M. fujianensis wood from plantation is of lightness, the air dried density is 0.462 g·cm^-3, lower than wood from natural forest by 2.38%, and the wood structure is looser than wood from natural forest, but the wood quality difference between plantation and natural forest is very small, and could not affect the application of the wood. The shrinkage coefficients of the volume and every direction of M. fujianensis wood were both small and had good dimensional stability and small deformation from plantation and natural forest. The composite strength of M. fujianensis wood from plantation was 132.55 Mpa, closed to the value 134.26 Mpa from natural forest, and belonged to low level and approached to middle level. The wood can be used as the non-structure material of furniture and interior decoration.(4) Taper equation proposed by Tong J Q et al(2000) is the best equation for both of the stem of M. fujianensis from the mixed and pure plantation. The mean breast height form factor of M. fujianensi in the mixed plantation is 0.520, higher than that in the pure plantation (0.508). The mean height-diameter ratio of M. fujianensi in the mixed plantation is 0.953, higher than that in the pure plantation (0.652), and the taperingness of M. fujianensi in the mixed plantation is lower than that in pure plantation.